The idea of a slot waveguide amplifier based on erbium-doped tellurite glass is first theoretically discussed in this work. Choosing the horizontal slot for low propagation loss, the TM mode profile compressed in the insertion layer was simulated, and the gain characteristics of the slot waveguide amplifier were calculated. Combining the capacity to confine light locally and the merits of tellurite glass as an emission host, this optimized amplifier shows enhanced interactions between the electric field and erbium ions and achieves a net gain of 15.21 dB for the 0.01 mW input light at 1530 nm, implying great promise of a high-performance device.

In this work, Er-doped aluminum nitride (AlN), Pr-doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. Some new and interesting phenomena were observed. The peak at 480 nm was observed only for Er-doped AlN. However, for Er, Pr co-doped AlN, it disappeared. At the same time, a new peak at 494 nm was observed, although it was not observed for Er-doped AlN or Pr-doped AlN before. Therefore, the energy transfer mechanism between Er³⁺ and Pr³⁺ in AlN thin films was investigated in detail. Through optimizing the dose ratio of Er³⁺ with respect to Pr³⁺, white light emission with an International Commission on Illumination chromaticity coordinate (0.332, 0.332) was obtained. This work may provide a new strategy for realizing white light emission based on nitride semiconductors.

Ho³⁺/Yb³⁺: BaMoO₄ phosphors with different concentrations were fabricated by a gel combustion method. The upconversion (UC) luminescence, intrinsic optical bistability, and the corresponding mechanisms were reported for the present system. The optical thermometric properties based on red (⁵F₅→⁵I₈) and green (⁵F₄/⁵S₂→⁵I₈) emissions were studied. The sensing sensitivities could be tuned by manipulating the cooperative energy transfer process. The highest absolute sensitivity was 99 × 10 ⁴ K ¹ at 573 K, which is larger than that of many previous UC materials.

A large-mode-area (LMA) ytterbium-doped photonic crystal fiber (PCF) with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb³⁺/Al³⁺/F /P⁵⁺ co-doped silica glass containing 0.09 mol% Yb₂O₃ with an absorption coefficient at 976 nm up to 3.2 dB/m. The core glass with homogeneous distribution of Yb³⁺ ions and refractive index difference of 4 × 10 ⁴ compared with pure silica was prepared by the sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 ps pulse duration and 48.7 MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W (266 kW peak power) quasi-single-mode laser output with M² of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, stimulated Raman scattering, or thermal damage on the end facet of the fiber were observed.

We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate near-infrared femtosecond laser. Elemental analysis by an electro-probe microanalyzer demonstrates that the redistributions of Ca²⁺ and Yb³⁺ ions change dramatically with pulse energy, which are quite different compared with previous reported results. Confocal fluorescence spectra of Yb³⁺ ions demonstrate that the luminescence intensity changes obviously with the elemental redistribution. The mechanism of the observed phenomenon is discussed. This observation may have potential applications in the fabrication of micro-optical devices.